First of all vs Firstly vs Primarily

When to use each in English, with meaning, register, and examples.

First of all

Top 2,000 (common)

Firstly

Formal Top 3,000 (common) A2 adverb

Primarily

Top 2,000 (common) B2 adverb

Most formal: Firstly

	First of all	Firstly	Primarily
Pronunciation	🇬🇧 //fɜːst əv ɔːl// 🇺🇸 //fɜrst əv ɔl//	🇬🇧 /["/ˈfɜːstli/"]/ 🇺🇸 /["/ˈfɜːrstli/"]/	🇬🇧 /["/praɪˈmerəli//ˈpraɪmərəli/"]/ 🇺🇸 /["/praɪˈmerəli/"]/
Meaning	To start with; the first point to mention.	At the start of a list or explanation.	mainly; for the most part
Example	First of all, we need to discuss the budget for next year.	There are two reasons for this decision: firstly…	a course designed primarily for specialists
Register	Neutral	Formal	Neutral
How common	Top 2,000 (common)	Top 3,000 (common)	Top 2,000 (common)
CEFR level	-	A2	B2
Part of speech		adverb	adverb
Collocations	first of all, we need, first of all, let's discuss, first of all, thank you, first of all, I want to, first of all, remember	firstly and secondly, firstly then, firstly I would like	primarily concerned, primarily focused, primarily used, primarily for, primarily about
Antonyms	-	lastly, finally	secondarily, incidentally, subordinately
Common mistakes	Using it in the middle of a sentence instead of at the beginning., Confusing with 'firstly', which is more formal., Omitting 'of all' and saying only 'first'.	'Firstly' is not often used in informal contexts., Some learners confuse 'firstly' with 'first,' thinking they can use them interchangeably in all situations., Overusing 'firstly' when listing items can sound overly formal.	Confused with 'principally' which has a similar meaning but different usage., Using it in a negative context incorrectly, such as saying 'not primarily' when 'not mainly' is clearer., Incorrectly placing 'primarily' at the end of a sentence.
Usage notes	Often used to introduce the first point in a list. Appropriate in both spoken and written contexts. Avoid in very formal settings.	Use 'firstly' to introduce the first point in formal writing or speeches. Avoid in casual conversations; 'first' is often preferred instead.	Use 'primarily' when you want to focus on the main reason or purpose; it's suitable in both spoken and written English but is more common in formal contexts than casual conversation.

See it in real clips

Yes. First of all, you're all done.

Agatha Christies Poirot › S1 E1

First of all. . .

Yes. First of all, you're all done.

Agatha Christies Poirot › S1 E1

First of all. . .

First of all

The Lord Of The Rings › The Fellowship Of The Ring

Do you know how the Orcs first came into being?

Firstly

Frequently asked questions: First of all vs Firstly vs Primarily

What's the difference between First of all, Firstly, and Primarily?

First of all: To start with; the first point to mention. Firstly: At the start of a list or explanation. Primarily: mainly; for the most part

Which is more formal: First of all, Firstly, and Primarily?

Firstly is the most formal of these.

Which is more advanced: First of all, Firstly, and Primarily?

Primarily is the highest level, at B2, on the CEFR scale.

Can you show an example of each?

First of all: First of all, we need to discuss the budget for next year. Firstly: There are two reasons for this decision: firstly… Primarily: a course designed primarily for specialists

Can I use First of all, Firstly, and Primarily interchangeably?

Not always. First of all, Firstly, and Primarily are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.